wc_get_product_id_by_sku() returns 0 for products added programatically via update_post_meta

The problem was that I didn’t create product with WC_Product object. When I create product with this object it works.

for instance

$product = new WC_Product; 
$product->set_name("my product");
$product->set_sku("345678");
$product->save();

Then I can easity get the ID of the product by SKU

$post_id = wc_get_product_id_by_sku('345678');